глобальная переменная

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
</head>
<body>
<script>
var val = 'This is a global variable';
document.write(val);
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
</head>
<body>
<script>
var val = 'This is a global variable';
document.write(val);
</script>
</body>
</html>